Researchers from Australian National University have developed the ability to move particles over distances of up to 1.5 meters, using a hollow laser beam to trap light-absorbing particles in a “dark core.” The particles are then moved up and down the beam of light, which acts like an optical “pipeline.”

“When the small particles are trapped in this dark core very interesting things start to happen,” said Professor Andrei Rode. “As gravity, air currents, and random motions of air molecules around the particle push it out of the center, one side becomes illuminated by the laser while the other lies in darkness. This creates a tiny thrust, known as a photophoretic force that effectively pushes the particle back into the darkened core. In addition to the trapping effect, a portion of the energy from the beam and the resulting force pushes the particle along the hollow laser pipeline.”

Practical applications for this technology include directing and clustering nanoparticles in air, micro-manipulation of objects, sampling of atmospheric aerosols, and low-contamination/non-touch handling of sampling materials for transport of dangerous substances and microbes in small amounts, he said.